Certain existing patient monitoring systems include biological sound sensors that capture patient bodily sounds (e.g., heart, breathing, digestive system sounds, etc.) and physiological monitors which process the captured sounds to determine physiological parameters. Such systems generally rely on a robust connection between the sensor and the patient to reliably detect and process the targeted bodily sounds. As such, a faulty or unstable connection between the sensor and the patient (e.g., a “probe-off” condition) can lead to a number of problems, particularly where the patient monitor or medical personnel are not made aware of the issue.
When the physiological monitor is not aware of a faulty connection between the sensor and patient, the monitor may misinterpret readings detected by the sensor. For example, the monitor may indicate false alarm conditions. In one instance, where the system is configured to detect patient breathing sounds and determine a corresponding respiratory rate, the monitor may falsely determine that the patient is not breathing, instead of merely indicating that the sensor has detached from the patient's skin. The system may additionally detect significant amounts of environmental noise due to a probe-off condition, and then improperly present the detected noise as physiological signal. Moreover, medical personnel may similarly misinterpret results presented by the monitor when the personnel are not aware of a faulty connection, possibly leading to misdiagnoses or other issues.
For these and other reasons, there is a need for an acoustic physiological sensor having reliable and straightforward probe-off detection capability.